My Fish bar

Ichthys · Aug 5, 2010

Herbie

holdendaniel said:
i switched the aga megaflow to the herbie style(1"drain with gate valve, and 3/4 emerg. ran new 3/'4 return line up back of tank........dead silent you can only hear the pump huming ALL YOU AGA MEGAFLOW USERS SWITCH IF YOU WANT IT DEAD QUITE

Hi,
I am absolutely NOT an expert on any of this stuff, and it seems by reading your posts that you are very knowledgeable about reef stuff, but you posted something that caught my eye. A 1" main drain under full siphon due to valve, and a 3/4" emerg back up, and only one? This seems like water on the floor waiting to happen. From what i understand, a bulkhead under full siphon drains much more GPH than a regular drain with turbulent air mixed flow. A 1" Herbie can flow 600-800 GPH. Should the 1" fail due to clog or valve issues, or snails or whatever, the seond and THIRD drains of a tradiational Herbie take the flow and wet floors are averted. Having only 1 emerg drain is a gamble, albeit a remote one. Having that drain only be 3/4 is a real gamble. If you are flowing your main 1" siphon at anywhere close to capacity then there is no way a 3/4 could handle it in the event of a clog or failure.
Again, this is my limited understanding from reading literature, not from actual experience, so forgive me if I am wrong..
Ichthys
PS one reason I am so interested in this is because if this is reliable, then I want to do it, put a 3/4 BH in my overflow and go Herbie! I throttled my main drain for a few minutes one night and it went dead silent, but I was scared to leave it throttled with no emerg drain, and i have no room for 2 more 1" BH's in my overflow. But a 3/4 BH i could do....

holdendaniel · Aug 6, 2010

i have a ehiem 1260 with 6' of head(500gph) i have lids on my overflow box the only way i could have a 3rd drain would be adding a pipe over the back ? ive had it running for a while like this only issue is goby sliping trough the slits on overflow i can close my 1 " off and my 3/4 handles the flow

Ichthys · Aug 6, 2010

Herbie

holdendaniel said:
i have a ehiem 1260 with 6' of head(500gph) i have lids on my overflow box the only way i could have a 3rd drain would be adding a pipe over the back ? ive had it running for a while like this only issue is goby sliping trough the slits on overflow i can close my 1 " off and my 3/4 handles the flow

at roughly 500gph, I can see the 3/4 would just barely handle the flow once it goes full siphon, but the tolerance is very tight and the margin for error very small. According to a paper I read on flow rates, a 3/4 under full siphon can flow 497GPH and less than 200 when not under siphon. I suppose what all this means is that you sir have bigger kahunas than I, lol. I am not willing to take the chance of flooding the bedroom as it would be the end of reef keeping in my house lol. Seriously though, it is working for you now, but slight changes in flow of your return pump, or build up in the drain pipes could prove problematic, you are operating on a very tight tolerance.

Here is the study that was done on bulkheads and flow rates.
http://www.wetwebmedia.com/BulkheadFloRateArt.htm

Ichthys